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Respiratory and cardiac motions represent important sources of image degradation in both PET and computed tomography (CT) studies that need to be taken into account and compensated to improve image quality and quantitative accuracy. This review describes the hardware needed to perform respiratory and cardiac gating with PET and PET/CT systems. In particular, most of the proposed motion-tracking devices for the management of respiratory, cardiac, and multidimensional movements are described and compared. Some advanced applications in PET and PET/CT made possible by the gating technology are considered and analyzed.

To exploit the sparsity in transform domain (e.g. wavelets), the image deconvolution can be typically formulated as a e 1 -penalized minimization problem, which, however, generally requires proper selection of regularization parameter for desired reconstruction quality. The key contribution of this paper is to develop a novel data-driven scheme to optimize regularization parameter, such that the resultant restored image achieves minimum prediction error (p-error). First, we develop Stein's unbiased risk estimate (SURE), an unbiased estimate of p-error, for image degradation model. Then, we propose a recursive evaluation of SURE for the basic iterative shrinkage/thresholding (IST), which enables us to find the optimal value of regularization parameter by exhaustive search. The numerical experiments show that the proposed SURE-based optimization leads to nearly optimal deconvolution performance in terms of peak signal-to-noise ratio (PSNR).

Despite the widespread use of ultrasound, the modality often suffers from image degradation. This study seeks to model and understand the mechanism behind reverberation, a source of clutter. Water tank experiments were performed on ex vivo goat abdominal wall tissue to measure magnitude of reverberation clutter. In addition, matched stained cross-sections of the goat abdominal wall samples were used to evaluate tissue factors such as relative amount of tissue types, tissue thickness, and number of tissue layers. A nested model analysis was performed to explore which factors affect clutter magnitude. Most of the variability was attributed to depth (R-squared of 0.777 with depth alone), although histology factors were found to significantly improve the model (R-squared of 0.861 including histology factors).

This paper uses an budgeting approach to examine the proposed X-ray Surveyor’s imaging quality. The paper presents a budget which is the same structure as that of the Chandra X-ray Observatory. The budget is populated with terms that can be expected to be the same as that of Chandra, namely the contributions due to aspect solution and alignment between the mirrors and focal plane detectors. An allocation for dynamic induced image degradation is then introduced, to allow for contribution due to the optics from all sources to be determined, ~0.44 arcseconds. This value is compared with the current state of the art, which is considerably in excess of 0.5 arcesconds. The role and possibility of adjustable optics for the X-ray Surveyor is discussed.

This paper presents new method for classification of type of image degradation based on the Riesz transform and BRISQUE no-reference quality measure. Riesz transform has great properties and it can be used in many applications. Some of its benefits are: the ability to construct family of steerable wavelets with arbitrary order and any number of dimensions and it can bring the algorithm of filter banks with perfect reconstruction and also go to dimensions higher than two. Statistical properties of MSCN coefficients used by BRISQUE change in presence of distortion and by quantifying this changes with features calculated by using GGD and AGGD model the class of distortion can be determined. We calculated 18 statistical features out of spatial coefficients defined by BRISQUE measure and 19 parameters out of Riesz coefficients to get 37 features in total and then used features as input in SVM regressor in order to identify the type of image degradation. Then, we compared new method with BRISQUE method by using McNemar's statistical test to show statistical significance of our method.

Medical images like ultrasound images, X-ray images and mammographic images of widespread use in the detection of numerous diseases. But these images are not free from noise and may be blurred due to some known or unknown factors. To remove noise and blur from such images we need various restoration techniques. A number of methods are available for this purpose depending upon the type of noise, type of blur and type of images. With no knowledge for the cause of image degradation, image restoration is a technique that regains the image. Image restoration is applied to bring back the debased image without any prior knowledge about the source of degradation. In this paper, various applications of image restoration related with areas of medical imaging are discussed.

Direct detector device (DDD) cameras dramatically enhance the capabilities of electron cryomicroscopy (cryo-EM) due to their improved detective quantum efficiency (DQE) relative to other detectors. DDDs use semiconductor technology that allows micrographs to be recorded as movies rather than integrated individual exposures. Movies from DDDs improve cryo-EM in another, more surprising, way. DDD movies revealed beam-induced specimen movement as a major source of image degradation and provide a way to partially correct the problem by aligning frames or regions of frames to account for this specimen movement. In this chapter, we use a self-consistent mathematical notation to explain, compare, and contrast several of the most popular existing algorithms for computationally correcting specimen movement in DDD movies. We conclude by discussing future developments in algorithms for processing DDD movies that would extend the capabilities of cryo-EM even further.

Introduction: Caries under restorations is the most common reason for re-treatment and replacement in restorative failures. To avoid failures of fixed dental prostheses, it is important to diagnose caries under it earlier. Without image degradation and metal artifacts, Cone Beam Computed Tomography (CBCT) can be the solution to detect caries without removing fixed dental prostheses. Aim: The aim of this study was to determine the efficacy of CBCT in detecting caries under fixed dental prostheses. Materials and Methods: Each specimen was scanned with CBCT for evaluation of secondary caries under fixed prostheses. Exposure parameters were 60 kVp and 3mA. Field of View (FOV) used was 8cm X 8cm. According to International Caries Detection and Assessment System (ICDAS) criteria, six Grade 6 carious extracted teeth were selected. All teeth were prepared with four different specimens - full metal, metal-ceramic, full ceramic and metal-acrylic crowns for each tooth. Each specimen was scanned by CBCT. T-test was performed for mean gray value differences between caries and noncaries regions of each material. Gray values were recorded and evaluated for different parameters using two-way analysis of variance. Results: Significant differences were found with respect to material (full metal, metal-ceramic, full ceramic and metalacrylic) and situation (caries/noncaries) (p

In this paper, we conduct research on the image de-noising algorithm based on the Wiener filtering and the edge modeling. Image restoration is a norm and the noise pollution observation to e stimate the original image in the image, the purpose is to restore the decay and loss of high frequency components. In real applications, the image degradation process is very complicated, it is difficult to de scribe with accurate mathematical model and therefore the applicable scope of the core traditional image restoration technology is limited. Under this background, we propose the new perspectives of the issues tha t will be meaningful and necessary.

Scattered radiation is a major cause of image degradation in modern cone-beam computed tomography (CBCT) scanners, both in the medical field as well as in non-destructive testing. In this work, we present a novel method for scatter correction in CBCT based on temporal primary modulation. In contrast to primary modulation methods in the spatial domain reported in the literature, temporal modulation does not suffer inaccuracies in the scatter image caused by overlapping spectral copies. Additionally, it is shown that the maximum detectable frequency in the scatter function can be increased by a factor of two compared to spatial primary modulation methods. Moreover, the measuring time is not increased. We demonstrate first experimental results obtained with an industrial CBCT scanner employing our new scatter correction method.

In this paper, a new precharging method without any side effects is proposed to overcome image degradation caused by insufficient charging times. This work explains why the precharging method can compensate for short charging times. However, side effects of the precharging method in the form of horizontal line artifacts are addressed, wherein line artifact-compensating precharging (LCP) is presented to mitigate the side effects. Behavioral modeling is employed to investigate the side effects by estimating transient responses of a liquid crystal display. The LCP proves that it can dramatically reduce line artifacts caused by precharging because the brightness difference of adjacent pixels does not exceed 1.0.

Narrow-band interference (NBI) suppression is an important technique in the low-frequency synthetic aperture radar (SAR). NBI sources either intentional or unintentional can mask the SAR signals and cause image degradation. According to the different characteristics of the spectra between the NBI and the SAR signals, a new method using subband spectral cancellation is applied to suppress the NBI. In contrast to the conventional suppression method performed on the raw data, this letter deals with the focused SAR image. By subtracting different range subband spectra of the SAR image, the NBIs are obtained and cancelled. The proposed method does not need to detect and estimate the parameters of the NBI and is easy to put in practice. Its performance is tested on the real data acquired by an experimental SAR system at P-band.

This paper presents a simple and efficient index coding method to reduce the storage cost for indexed colour images. The method exploits the high degree of similarity among neighbouring indices by using a sorted palette. The indices that were compressed by the colour image quantisation are classified into three categories. Every category employs a different encoding rule to process the indices. To compress the indices of the second category, two optional approaches are provided. Experimental results show that the proposed method can significantly cut down the number of bit rates without incurring extra image degradation.

To compare visualization using whole-heart coronary magnetic resonance angiography (CMRA) acquired during a single breath-hold (BH) with that using conventional respiratory-gated (RG) CMRA.The CMRAs of 14 healthy subjects under either BH or RG conditions were studied using a 1.5 T system equipped with a whole-body phased-array coil and 16-channel receivers. The BH examination was accelerated using parallel imaging (PI) by factors of 2.5 and 2 in the phase and section directions, respectively. For the RG examination, a PI factor of 2 was used only in the phase direction. The visualization quality of 15 coronary segments using each condition was evaluated with a five-point scale (0-4). Differences between two conditions were compared at segments with an average score greater than 2 in RG-CMRA.The average examination time for BH and RG acquisition scans was 34 s and 11 min 31 s, respectively. Ten segments (segments 1-3, 5-9, 11, and 13) had average scores higher than 2 in RG-CMRA. Of these, BH-CMRA had significantly lower scores than RG-CMRA at six segments (segments 1, 5-8, and 11) after correction for multiple comparisons (p0.005). However, in BH-CMRA, proximal segments (segments 1-2, 5-7, and 11) showed average scores over 2, indicating marginally acceptable image quality.Compared with the relatively limited degree of image degradation with RG-CMRA, the present data suggest that BH-CMRA would be useful for screening and as an adjunct to RG-CMRA that is occasionally incomplete.

An earlier revision of this paper was mistakenly submitted for publication as the final draft. Unfortunately, this was not discovered until after it appeared in print [1]. The correct version of the paper is presented here.

The newly introduced Big Bore computed tomography (CT) has a possibility to increase the tube current product scan time (mA s) for compensation of image degradation due to larger gentry opening without sound guideline. The objective of this paper is to derive optimal scan conditions for Big Bore CT scanner, mainly relating to the dose of diagnostic CT. The weighted CT dose index (CTDI(w)) was estimated at five typical protocols, such as head and neck, brain, paediatric, chest and abdomen. Noises were analysed in a circle of 1 or 2 cm of diameter in CT image slice. The results showed that measured CTDI(w) values generally follow the theoretical rule at all scanning conditions of every protocol. Although image noises decrease with increment of mA s, analysed image noises do follow the theoretical rule, but only in specific protocols. This phenomenon is presumed to result from the photon energy spectra arriving at the detection system of the Big Bore scanner.

Before the advent of fast-scanning multidetector-row computed tomography (CT) technology, thoracic CT studies were exclusively used for the morphologic assessment of thoracic organs, as the concurrent examination of the heart was hampered by image degradation from cardiac motion artifacts. The introduction of fast rotation speed and dedicated cardiac reconstruction algorithms has opened new possibilities for chest imaging, starting with the possibility to integrate cardiac morphologic and functional information into a diagnostic CT scan of the chest. Initiated with 16-slice multidetector-row CT, this concept of integrating morphology and function has been further simplified with 64-slice CT scanners, thus allowing radiologists to provide vital information in the management of patients with a wide variety of acute or chronic respiratory disorders. Because this CT technology offers the possibility of generating high-resolution and motion-free images of the coronary arteries, evaluation of the coronary arteries during CT examinations of the chest should further widen the clinical applications of CT for respiratory patients, keeping in mind that cigarette smoking is a shared risk factor for both impaired lung function and cardiovascular events. The recent advent of high temporal resolution and high pitch modes with dual-source CT simplifies the concept of integrated cardiothoracic imaging, introducing non-electrocardiographic-gated coronary artery imaging. The purpose of this article is to review the successive approaches of these redefined borders of thoracic imaging.

In this paper, we propose a multiple classifier combination method based on image degradation modeling to improve recognition performance on low-quality images. Using an image degradation model, it generates a set of classifiers each of which is specialized for a specific image quality. In recognition, it combines the results of the recognizers by weighted averaging to decide the final result. At this time, the weight of each recognizer is dynamically decided from the estimated quality of the input image. It assigns large weight to the recognizer specialized to the estimated quality of the input image, but small weight to other recognizers. As the result, it can effectively adapt to image quality variation. Moreover, being a multiple-classifier system, it shows more reliable performance then the single-classifier system on low-quality images. In the experiment, the proposed multiple-classifier combination method achieved higher recognition rate than multiple-classifier combination systems not considering the image quality or single classifier systems considering the image quality.

Overlap-blur is caused by the relative movement of high speed between the camera and the object during the exposure process, which is one of the most common phenomenons of image degradation during the criminal detection forensics work. Based on the analysis of the overlap-blurred image’s characteristic, a coded-shutter model is proposed to approximate the nature of overlap-blur. As the first attempt, using the coded-shutter model, an image deblurring algorithm is designed for the restoration of the overlap-blurred images. The experiment results show the validity and rationality of the coded-shutter model for deblurring the overlap-blurred images. When tested on the real overlap-blurred photographs, the proposed algorithm can restore the information of interest in the blurred images better, which demonstrates the higher practical value of the algorithm.

Two related formulations are proposed for target-oriented joint least-squares migration/inversion of time-lapse seismic data sets. Time-lapse seismic images can be degraded when reservoir overburden is complex or when acquisition geometries significantly differ, because the migration operator does not compensate for the resulting amplitude and phase distortions. Under these circumstances, time-lapse amplitudes are poor indicators of production-related changes in reservoir properties. To correct for such image degradation, time-lapse imaging is posed as joint inverse problems that utilize concatenations of target-oriented approximations to the linear least-squares imaging Hessian. In both formulations, spatial and temporal constraints ensure inversion stability and geologically consistent time-lapse images. Using two numerical time-lapse data sets, we confirmed that these formulations can attenuate illumination artifacts caused by complex overburden or geometry differences, and that they yield better-quality images than obtainable with migration.

As high quality image is required for digital cameras in recent use, the image stabilization technique has drawn much attention to prevent image degradation from shaky disturbance by users. In this paper, the optical image stabilization (OIS) system for DSLR (Digital Single Lens Reflex) camera is considered. First, the analytic model of an OIS system is presented to demonstrate the mechanism of image destabilization due to unknown disturbance that causes blurry images on CCD sensor. Then, to enhance the stabilization performance, a sliding mode control based on the min-max nonlinear control is introduced. Through the experiments and simulations, the effectiveness of the proposed method will be verified.

In the system of X-ray radiograph, the scattered X-ray induces the depression and degradation of the image quality, and badly influences the detecting sensitivity. After studying mechanism of image degradation, and analyzing the scattering polarization, a new restoration method based on the blind separation and wavelet transform was raised. An ICA (Independent Component Analysis) model was firstly constituted based on the radiograph mechanism. To satisfy to the statistically independence of blind separation, the sub-band images by wavelet transform were utilized as estimating source. We utilized the least mutual information entropy as the criteria for blind separation and deduced to the optimization estimation. The experimental results show that the method can effectively depress the scattering and improve the contrast.

The high convenience of data collection by helical scanning, such as making multi planner reformat (MPR) and shortening scan time, means that the technique is widely used to diagnose various body parts. However, non-helical scanning is still a main current for plane brain computed tomography. The possibility of diagnosing acute cerebral infarction by helical scanning MPR was examined. It was found that image degradation in helical scanning had little influence on the physical evaluation of the characteristics of modulation transfer function and the noise power spectrum, etc. In the evaluation of the ischemic change occurring at the early stage made by examination of clinical images, the result was almost equal to that obtained by non-helical scanning, as the reported sensitivity was 52% and the specificity was 95%. This suggested that brain helical scanning MPR might be applied clinically. However, a disadvantage was confirmed as helical scanning had a higher exposure dose than non-helical scanning at the start and end of scanning. The results of this study indicated that helical scanning demonstrates sufficient convenience for the assessment of acute cerebral infarction at the basal nucleus level.

Objective To familiarize the reader with the fundamental concepts of partial parallel imaging (PPI); to review the technical aspects of PPI including calibration scan, coil geometry, and field of view (FOV); and to illustrate artifacts related to parallel imaging and describe solutions to minimize their negative impact. Results PPI has led to a significant advance in body magnetic resonance imaging by reducing the time required to generate an image without loss of spatial resolution. Although PPI can improve image quality, it is not free of artifacts, which can result in significant image degradation. Knowledge of these artifacts and how to minimize their effect is important to optimize the use of parallel imaging for specific body magnetic resonance imaging applications. Conclusions The reader will be introduced to the fundamental principles of PPI. Common imaging characteristics of PPI artifacts will be displayed with an emphasis on those seen with image-based methods, the principles behind their generation presented, and measures to minimize their negative impact will be proposed.

In this paper, we propose from media production environment using meta-data based on advanced authoring format(AAF). The media production system becomes digitalized since the image degradation and data storage should be minimized. For transmitting various contents without loss of meta-data. Editing decision list(EDL)is used in the current broadcasting and cinema environment, which results in inefficient performance. We compared the proposed AAF with the existing EDL cut, and tested successful transmission of the metadata. Based on the experimental results, the proposed AAF contains more video information than EDL.

PURPOSE To examine the feasibility of reducing exposition in CT examinations by applying a prototype device for tube current modulation with the image quality remaining unchanged. PATIENTS AND METHODS The prototype device for tube current modulation was integrated into a Somatom Plus 4 CT scanner (Siemens). The method is based on anatomy-oriented modulation of the tube current. The attenuation of the X-ray beam by the patient's body was determined online, the tube current was adapted to changing anatomy after a delay of 180 degrees. In ten patients undergoing radiotherapy, four identical scans of the shoulder region were carried out with and without tube current modulation. For determining dose reduction, mAs product of both scans were compared. The evaluation of noise artifacts, low contrast detectability and overall image quality was performed by four radiologists in a blinded fashion. RESULTS Patient doses could be reduced by 38% on an average. Scans with tube current modulation were superior to scans without it as to noise (75%), low contrast detectability (51%), artifacts (69%), and overall image quality (71%). CONCLUSIONS A significant reduction in exposition during CT can be achieved by anatomy-oriented tube current modulation without image degradation.

For the lenses proposed by J. Pendry and N. Engheta, the image degradation that occurs owing to deviation of the parameters of the metamaterial used from the parameters required to form the image is investigated. It is shown that a single-layer structure permits a 2% deviation of the parameters from the specified values and that the real parts of deviations may affect the image stronger than the presence of losses. The multilayer lenses obtained by the addition of new layers to a single-layer lens are shown to be less stable against deviations.

Based on our original LCD interface technology, the Vertically Differential Encoding (VDE) method for LCD panel interface that reduced the EMI by −15dB [1], we have developed a Color Differential VDE (CD-VDE) with fixed length coding as a low-power LCD interface that can reduce the clock frequency to half without noticeable image degradation. We have reduced the power consumption by 14% for a 14-in LCD with SXGA+ resolution by developing an FPGA with the CD-VDE algorithm.

The purpose of this study was to determine whether prospective adaptive navigator correction improves slice position invariability while maintaining image quality and enables efficient cine display observation on gadolinium-enhanced multiphasic thin-slice 3D MRI of the liver.The study consisted of two parts: a phantom study and a clinical study. To explore the effect of navigator correction, a phantom was imaged in the resting state and in continuous movement. In the clinical study, gadolinium-enhanced four-phase 3D spoiled turbo field-echo images (3-mm thickness with no intersectional gap, 60 slices for whole liver) were retrospectively assessed. The subjects were 83 patients with 130 focal hepatic lesions randomized into two groups: with (n = 45) and without (n = 38) navigator correction. Images were qualitatively assessed by two blinded radiologists using a three-point slice position invariability scale for liver and focal hepatic lesions. Image degradation due to motion or artifacts was qualitatively assessed.Phantom images were obtained with excellent slice position invariability while image quality was maintained with navigator correction. Navigator correction substantially degraded the quality of the images of two patients (one with a large amount of ascites and the other with a large hepatic cyst). In the other 81 patients, the degree of slice position invariability for the liver was greater (p0.001) with (score, 2.84 +/- 0.43 [SD]) than without (score, 2.37 +/- 0.75) navigator correction. For focal hepatic lesions, slice position invariability also was greater (p0.0001) with (score, 2.95 +/- 0.21) than without (score, 2.18 +/- 0.88) navigator correction. No difference in degree of image degradation was found with or without navigator correction.Prospective navigator correction improves slice position invariability for cine display observation while preserving image quality for gadolinium-enhanced multiphasic thin-slice 3D MRI of the liver.

I read with interest the article by Andre et al [1] titled “Toward Quantifying the Prevalence, Severity, and Cost Associated With Patient Motion During Clinical MR Examinations.” In their article, the authors eloquently demonstrated that motion artifacts represent a frequent cause of image degradation in MRI and impose a significant financial burden on radiology departments. There are some additional points worth mentioning. The authors recommended more investment in research and software packages for motion correction, but it would be interesting to know how often the currently available motion correction sequences and softwares were used in the study. Some motion correction techniques, such as PROPELLER, have been shown to be very useful in clinical settings, are available on the majority of imaging platforms [2], and are commonly used in moving patients. Another example is the echo-planar imaging fluid-attenuated inversion recovery sequence, which has shown to produce qualitative and quantitative results comparable with those obtained using conventional fluid-attenuated inversion recovery imaging in the

In attempting to clarify the mechanism of ultrasound B-mode in vivo image degradation, recent studies reveal that both multipath scattering and phase-aberration are primary causes of image degradation. To compare the relative contributions of these two effects on imaging, it is important to differentiate whether image degradation is from multipath scattering, phase-aberration or a combination of both. Our aperture domain model image reconstruction (ADMIRE) algorithm, which identifies and suppresses clutter sources, enables us to separate these two effects. Using ADMIRE, we performed simulations to test whether aberration measurements are corrupt in the presence of multipath scattering. We also evaluated ADMIRE in the presence of phase-aberration. We then modified the original ADMIRE, by adapting estimated aberration profiles from pre-ADMIRE data into the original model (referred to as adaptive ADMIRE). We also performed in vivo studies with the two algorithms, comparing results using image quality metrics and aberration profile characterization. Contrast improvement relative to the original B-mode, with ADMIRE and adaptive ADMIRE, are 7.1±2.5 dB and 6.6±2.7 dB, respectively. The aberration profiles' FWHM after ADMIRE and adaptive ADMIRE are 4.0±.28 mm and 2.8±1.3 mm, respectively. The average RMS post-ADMIRE and post-adaptive ADMIRE are 16±5.4 ns and 20±6.3 ns, respectively. Both simulations and in vivo results suggest that ADMIRE suppresses phase-aberration.

PURPOSE: To assess the effect of media opacities on thickness measurements of the peripapillary retinal nerve fibre layer (pRNFL) and macular inner retinal layer (mIRL) performed with spectral-domain optical coherence tomography (SD-OCT) using a set of filters with known optical density. METHODS: Spectral-domain optical coherence tomography volume scans of the optic disc and the macular area were performed in 18 healthy volunteers, using Topcon-3DOCT-1000 Mark II. A set of five filters with optical density ranging from 0.04 to 0.69 was used. The correlation was calculated between the percentage change in thickness measurements (%ΔpRNFL and %ΔmIRL) and the change in optical density. All scans and measurements were performed in duplicate by one operator. RESULTS: Eighteen right eyes of 18 healthy volunteers were included in this study. Percentage decrease in pRNFL and mIRL thickness correlated with change in optical density (Spearman's rho r = 0.82; p < 0.001 and r = 0.89; p < 0.001, respectively). The measured decrease in pRNFL thickness differed from the decrease in mIRL thickness, not only between individuals, but also within the same individual. CONCLUSIONS: Optical coherence tomography thickness measurements of both pRNFL and mIRL are influenced by image degradation caused by optical density filters as a model for media opacities. An underestimation of the thickness of these layers was observed, caused by a shift of retinal layer boundary placement due to image quality loss. This underestimation is not the same for each individual and also differed between the pRNFL and mIRL thickness measurements. These individual and interindividual differences demonstrate that an individual approach will be necessary to correct for this underestimation per layer.

U današnje vrijeme digitalni zapisi slika predstavljaju bitan izvor informacija te su podložni različitim vrstama degradacije zbog čega su razvijene različite metode poboljšanja kvalitete slika. Kako bi se ustanovila pojedina vrsta degradacije, u radu je predložena nova metoda za određivanje vrste degradacije slike koja se temelji na mjeri percepcijske kvalitete BRISQUE bez upotrebe izvorne slike te Rieszovoj transformaciji koja omogućava konstrukcije usmjerenih waveleta s proizvoljnim redovima i bilo kojim brojem dimenzija te omogućava savršenu rekonstrukciju. Nova metoda definira trideset i sedam parametara, osamnaest iz BRISQUE mjere te devetnaest iz koeficijenata Rieszove transformacije iz kojih se određuje vrste degradacije slike. Pri tome je mjera ispitivana u LIVE i VCL@FER bazi zasebno te u međusobnim kombinacijama ovih baza uz normalizaciju parametara na minimalne i maksimalne vrijednosti parametara izračunatih iz LIVE i VCL@FER baze uz pomoć treniranja sa strojevima s potpornim vektorima (SVM). Ispitana je statistička značajnost nove metode za određivanje vrste degradacije slike te uspoređena s postojećom BRISQUE metodom. U većini slučajeva se postižu statistički bolji rezultati nove metode, a najbolji rezultati se postižu ako se treniranje provodi na parametrima iz LIVE baze normaliziranim na parametre LIVE baze koja će i biti korištena prilikom određivanja vrste degradacije nepoznate slike. Nakon što se odredi vrsta degradacije nepoznate slike, na temelju određenih parametara percepcijske mjere kvalitete BRISQUE kod kojih je uočena pravilnost ponašanja (kod zamućenja smanjivanje vrijednosti parametara kako raste stupanj degradacije Gaussovim zamućenjem, tj. kod šuma porast vrijednosti parametara kako raste stupanj degradacije Gaussovim šumom) definira se standardna devijacija Gaussovog šuma ili Gaussovog zamućenja koja je ulazni parametar u algoritam za uklanjanje šuma (BM3D) odnosno zamućenja (Lucy-Richardson). Navedenim postupcima postiže se određivanje vrste degradacije slike te uklanjanje degradacije šumom i zamućenjem bez poznavanja izvorne slike te vrste i stupnja degradacije. Digital formats of images are nowadays very important source of information and are submissive to different kinds of distortions which is the reason why there exists a development of different methods of image quality enhancement. In order of identification of the type of degradation, the thesis presents innovative approach od defining the type of image degradation which is based on no-reference perceptual quality measure BRISQUE and Riesz transformation which allows constructions of oriented wavelets with arbitrary order and number of dimensions and enables perfect reconstruction. New method defines 37 parameters, 18 out of BRISQUE method and 19 out of Riesz transformation coefficients which define the type of image degradation. LIVE and VCL@FER bases were used separately and in combinations with normalization of parameters on minimal and maximal values of parameters calculated out of LIVE and VCL@FER bases using training with support vector machines (SVM). Statistical significance between new method for defining type of degradation and BRISQUE method is calculated. For the most of cases, statistical results of new method are better and the best results are achieved using parameters calculated in LIVE base normalized on the same base parameters and the LIVE base will be used for defining the type of image degradation for unknown image. After the type of image degradation is determined, based on certain parameters of perceptual quality measure BRISQUE where some kind of regularity is noticed ( in meanings of blur decreasing the value of parameters when the degree of Gaussian blur distortion is increasing, in meanings of noise the augmentation of values of parameters when the degree of Gaussian noise is increasing), standard deviation of Gaussian noise or Gaussian blur is determined and it is an input to an algorithm for noise removal (BM3D) or for blur removal (Lucy-Richardson). In this doctoral thesis determination of type of degradation and removal of blur and noise degradation is achieved without information of reference image or type or degree of degradation.

As for the problem that ground scenery image interfered causes its quality decreased, and in order to get high-quality data ground scenery, in this paper, firstly analyze the main factors of image degradation and then we adopt wiener filtering to recover image which is interfered by movement blurred and noise. The results show the effectiveness of method.

In cone beam CT (CBCT), imperfect patient immobility, caused by involuntary movements, is one of the most important causes of artefacts and image quality degradation. Various works in literature address this topic, but seldom is the nature of the movement correlated with the type of artefact and the image degradation in a systematic manner, and the correlation analyzed and explained.All three types of movements that can occur during a scan-nodding, tilting and rolling-were applied to a dry skull, in various manners from abrupt to gradual through the entire scan, at different times and angles, over a wide range of displacements. 84 scans were performed, with different skull movements, and the resulting images examined by two skilled radiologists, rated in a four-point scale and statistically analyzed. A commercial CBCT machine was used, featuring supine patient positioning.Different types of movements induce different artefacts, in different parts of the anatomy. In general, movement of short duration may lead to double contours (bilateral or monolateral depending upon the angle of the scan at which they occur), whereas gradual movements result into blurring.Not all movements cause motion artefacts that equally jeopardize the image. Rolling is the type of movement that most severely affects the image diagnostic value.These findings may help practitioners to identify the causes of motion artefacts and the resulting image degradation, and remediate them, and manufacturers to improve the patient-positioning devices.

GIF image is one of the most widely applied images on the Internet. This article puts forward selective encryption algorithms for degradation mode based on coding features of GIF image and presents encryption effect picture through experience and then analyzes its safety, enciphered data size, format compatibility and compression ratio.

To evaluate visual blur as a mechanism for modulating eye shape.Chicks wore a unilateral full goggle or one of several goggles modified with apertures. After 2 weeks, eyes were measured with refractometry, ultrasound, and calipers, and three retinal regions were assayed for dopamine and DOPAC (3,4-dihydroxyphenylacetic acid).Goggled eyes were diffusely enlarged or enlarged predominantly along the axial dimension, depending on the goggle. Myopia developed under goggle types inducing primarily axial growth and under some of the goggles inducing diffuse eye expansion. Enlarged eyes remained emmetropic beneath other goggles that caused diffuse eye expansion. Reductions in retinal dopamine and DOPAC were proportional to the eye growth and refraction effects.Localized image degradation can cause myopia with predominantly axial expansion, myopia with more diffuse vitreous chamber expansion, or eye expansion without myopia. Robust expansion of the equatorial diameter alone was not observed. The associated alterations in retinal dopamine metabolism are consistent with a hypothesized role of dopaminergic amacrine cells in the visual regulation of eye growth. Besides refraction and overall size, visual blur can affect eye shape; but the goggle responses do not correspond to a simple summation of blur signals across the retina. Therefore, other mechanisms seemingly are needed to account for the full range of refractions and ocular shapes seen in chicks and, by analogy, in humans.